22nd International Symposium on
Principles and Practice of Declarative Programming

PPDP 2020

Virtual conference organized by University of Bologna, Italy, 8-10 September 2020

Part of BOPL 2020: The BOlogna Federated Conference on Programming Languages 2020


  • 13 papers have been accepted for presentation at the online conference.
  • Registration is now open (until 3 Sep 2020).

Overview of PPDP 2020

The 22nd International Symposium on Principles and Practice of Declarative Programming will take place online 8-10 September 2020. It will be organized by the University of Bologna, Italy. The exact format of the online conference is to be determined.

The PPDP 2020 symposium brings together researchers from the declarative programming communities, including those working in the functional, logic, answer-set, and constraint handling programming paradigms. The goal is to stimulate research in the use of logical formalisms and methods for analyzing, performing, specifying, and reasoning about computations, including mechanisms for concurrency, security, static analysis, and verification.

Submissions are invited on all topics related to declarative programming, from principles to practice, from foundations to applications. Topics of interest include, but are not limited to

  • Language Design: domain-specific languages; interoperability; concurrency, parallelism and distribution; modules; functional languages; reactive languages; languages with objects; languages for quantum computing; languages inspired by biological and chemical computation; metaprogramming.

  • Declarative languages in artificial intelligence: logic programming; database languages; knowledge representation languages; probabilistic languages; differentiable languages.

  • Implementations: abstract machines; interpreters; compilation; compile-time and run-time optimization; memory management.

  • Foundations: types; logical frameworks; monads and effects; semantics.

  • Analysis and Transformation: partial evaluation; abstract interpretation; control flow; data flow; information flow; termination analysis; resource analysis; type inference and type checking; verification; validation; debugging; testing.

  • Tools and Applications: programming and proof environments; verification tools; case studies in proof assistants or interactive theorem provers; certification; novel applications of declarative programming inside and outside of CS; declarative programming pearls; practical experience reports and industrial application; education.

The PC chair will be happy to advise on the appropriateness of a topic.

PPDP 2020 will be held in Bologna, Italy. Previous symposia were held at

The proceedings of previous instances of PPDP can be browsed at the DBLP Computer Science Bibliography.

Continuing a friendly tradition, PPDP 2020 will be co-located with the 29th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2020). This year also with the Microservices 2020 conference, forming BOPL 2020, the BOlogna federated conference on Programming Languages 2020.

Invited Speakers

  • TBD (BOPL invited speaker).
  • Ekaterina Komendantskaya (joint PPDP-LOPSTR invited speaker).
  • Dimitrios Vytiniotis (PPDP invited speaker).
  • Franco Barbanera and Ugo de'Liguoro (PPDP 2010 most influential paper).
    Two notions of sub-behaviour for session-based client/server systems: 10 years later.

Accepted Papers

  • Beniamino Accattoli, Ugo Dal Lago and Gabriele Vanoni.
    The Machinery of Interaction
  • Pablo Barenbaum and Eduardo Bonelli.
    Rewrites as Terms through Justification Logic
  • Luca Ciccone and Luca Padovani.
    A Dependently Typed Linear π-Calculus in Agda
  • Ankush Das and Frank Pfenning.
    Verified Linear Session-Typed Concurrent Programming
  • Paul Downen and Zena M. Ariola.
    A Computational Understanding of Classical (Co)Recursion
  • Maribel Fernandez and Janos Varga.
    Finding Candidate Keys and 3NF via Strategic Port Graph Rewriting
  • Alasdair Hill, Ekaterina Komendantskaya and Ronald Petrick.
    Proof-Carrying Plan Logic: a Resource Logic for AI Planning
  • Maja Kirkeby and Robert Glück.
    Inversion Framework: Reasoning about Inversion by Conditional Term Rewriting System
  • Beidi Li, Jochen Teizer and Carl Schultz.
    Non-monotonic Spatial Reasoning for Safety Analysis in Construction
  • Dylan McDermott, Maciej Piróg and Tarmo Uustalu.
    Degrading lists
  • Abhiroop Sarkar and Mary Sheeran.
    Hailstorm: A Statically-Typed, Purely Functional Language for IoT Applications
  • Mallku Soldevila, Beta Ziliani and Daniel Fridlender.
    Understanding Lua's Garbage Collection - Towards a Formalized Static Analyzer
  • Gonzague Yernaux, Wim Vanhoof and Laurent Schumacher.
    Experience Report: Moulinog: A Generator of Random Student Assignments Written in Prolog

Important Dates

  • 18.05.2020 AoE: abstract submission (extended)
  • 22.05.2020 AoE: paper submission (extended)
  • 22.06.2020: rebuttal period (48 hours)
  • 03.07.2020: notification
  • 21.07.2020: final papers
  • 08.09.2020: conference starts

Program Committee

Andreas Abel (co-chair) Gothenburg University, SE
Kenichi Asai Ochanomizu University, Tokyo, JP
James Cheney (co-chair) The University of Edinburgh, UK
Ugo Dal Lago University of Bologna, IT & INRIA Sophia Antipolis, FR
Thom Fruehwirth University of Ulm, DE
Michael Hanus Christian-Albrechts-Universität zu Kiel, DE
Jacob Howe City, University of London, UK
Fred Mesnard Université de la Réunion, FR
Hsiang-Shang Ko Institute of Information Science, Academia Sinica, TW
Meng Wang University of Bristol, UK
Henrik Nilsson University of Nottingham, UK
David Sabel Ludwig Maximilians University of Munich, DE
Claudio Sacerdoti Coen University of Bologna, IT
Ulrich Schöpp fortiss GmbH, DE
Martin Sulzmann Karlsruhe University of Applied Sciences, DE
Christine Tasson Université Paris Diderot & IRIF, FR
Peter Van Roy Université catholique de Louvain, BE

Call for Papers

The Call for Papers can be viewed or downloaded as

Submission Categories & Guidelines

Submission site: easychair.org/conferences/?conf=ppdp2020

Submission Categories

Submissions can be made in three categories: regular Research Papers, System Descriptions, and Experience Reports.

Submissions of Research Papers must present original research which is unpublished and not submitted elsewhere. They must not exceed 12 pages ACM style 2-column (including figures, but excluding bibliography). Work that already appeared in unpublished or informally published workshop proceedings may be submitted (please contact the PC chair in case of questions). Research papers will be judged on originality, significance, correctness, clarity, and readability.

Submission of System Descriptions must describe a working system whose description has not been published or submitted elsewhere. They must not exceed 10 pages and should contain a link to a working system. System Descriptions must be marked as such at the time of submission and will be judged on originality, significance, usefulness, clarity, and readability.

Submissions of Experience Reports are meant to help create a body of published, refereed, citable evidence where declarative programming such as functional, logic, answer-set, constraint programming, etc., is used in practice. They must not exceed 5 pages including references. Experience Reports must be marked as such at the time of submission and need not report original research results. They will be judged on significance, usefulness, clarity, and readability.

Possible topics for an Experience Report include, but are not limited to:

  • insights gained from real-world projects using declarative programming
  • comparison of declarative programming with conventional programming in the context of an industrial project or a university curriculum
  • curricular issues encountered when using declarative programming in education
  • real-world constraints that created special challenges for an implementation of a declarative language or for declarative programming in general
  • novel use of declarative programming in the classroom
  • programming pearl that illustrates a nifty new data structure or programming technique.

Supplementary material may be provided via a link to an extended version of the submission (recommended), or in a clearly marked appendix beyond the above-mentioned page limits. Reviewers are not required to study extended versions or any material beyond the respective page limit. Material beyond the page limit will not be included in the final published version.

Format of a submission

For each paper category, you must use the most recent version of the "Current ACM Master Template" which is available at https://www.acm.org/publications/proceedings-template. The most recent version at the time of writing is 1.70. You must use the LaTeX sigconf proceedings template as the conference organizers are unable to process final submissions in other formats. In case of problems with the templates, contact ACM's TeX support team at Aptara. Authors should note ACM's statement on author's rights which apply to final papers. Submitted papers should meet the requirements of ACM's plagiarism policy.

Requirements for publication

Due to the shift to an online event, registration fees will be decreased to cover only the costs of publication and online event hosting. At least one author of each accepted submission will be expected to attend and present the work at the conference. The pc chair may retract a paper that is not presented. The pc chair may also retract a paper if complaints about the paper's correctness are raised which cannot be resolved by the final paper deadline.

Review process

The reviewing is single-blind.



Proceedings will be published in the ACM International Conference Proceedings Series under ISBN 978-1-4503-8821-4, and will be available in the ACM Digital Library.


Program Chair

Andreas Abel
Department of Computer Science and Engineering
Gothenburg University

Local Organiser

Maurizio Gabbrielli
Department of Computer Science and Engineering
Bologna University